RAPID CITY, S.D. – By Spring 2027, thousands of daily commuters and tourists will see the first signs of a major South Dakota Department of Transportation reconstruction project – one of the largest in South Dakota – on Highway 16 and Catron Boulevard.

On Tuesday at Black Hills Energy building off Catron, South Dakota DOT officials held a public presentation outlining the project phases and timelines and answering questions.

The intersection will undergo a major remodel to a single point interchange – to move large amounts of traffic in limited space – with Highway 16B and Catron Boulevard passing underneath Highway 16. The new interchange will be similar to the one at Interstate 90 and Haines Avenue.

According to the DOT, the project weighs in with a price tag of $100 million, making it one of the largest and most expensive Department of Transportation projects in the state of South Dakota.

It’s anticipated construction will begin in the Spring of 2027.

“The interchange isn’t so unique to South Dakota,” said Steve Palmer, Engineering Supervisor, South Dakota Department of Transportation. “But you’re taking an at-grade intersection and trying to build a separate grade interchange to put traffic up and over.”

The construction will impact the major thoroughfare for tourists to Mount Rushmore and the hills, medical travelers, dozens of businesses and new developments, as well as thousands of year-round residents.

The annual average daily traffic through the intersection south to Mount Rushmore is just more than 18,000.

Palmer said the DOT has developed plans to minimize congestion and keep traffic flowing by trying to keep two lanes open and two left turn lanes during construction.

“We can’t do it all the time, we can’t do it a hundred percent of the time but we’re trying to maintain a dual left as long as we can, especially during tourist season,” Palmer said.

The project will include three construction projects and span years and include detours, overpass construction, road resurfacing and more. Exact dates will be shared when available. Detailed plans and traffic disruption expectations are available on the South Dakota Department of Transportation website.

Project 1 will include the Intersection of U.S. Highway 16 and Promise Road and include grading and resurfacing, curb and gutter, sewer, lighting, ramps and sidewalk. The project is slated for 2026 to 2028.

Project 2 will run from 2029 to 2030 and include installing ramps and related construction and install bridges on 16 over 16B and Catron.

Project 3 will run from 2031 to 2032 and focus on reconstruction of 16B and Catron Boulevard.

According to the South Dakota Department of Transportation, that busy intersection and corridor is key to regional and local networks for commuters and tourists. Future development of the area will drive even more traffic to the intersection which already has a high crash rate (45 crashes between 2021 and 2025) which is consistent with congestion, unexpected queue lengths and weather-related road conditions.

The Catron/16 project was first identified in 2016 as a preferred alternative. Following further studies and public meetings, the project was finalized in 2021 leading to the design and detail work.

South Dakota DOT worked closely with Utah DOT, which had built several similar projects and the South Dakota plan was modeled.

“This one was very unique,” Palmer said. “We didn’t quite know how to build this – you take one road and put it over the top.”

Leading up to project the DOT works with utilities, the Rapid City Fire Department, surrounding landowners and businesses, tourism leaders and the City of Rapid City.

Several meetings during the different phases of construction are planned.

More information about the project can be found via this qr code.

This section of Hwy. 16 will have an overpass spanning over traffic from Catron Boulevard.